More vs2019 minor warnings cleanup (#675)

api/include/opentelemetry/context/context.h

@@ -140,7 +140,7 @@ private:
       next_  = nostd::shared_ptr<DataList>{nullptr};
     }
 
-    DataList &operator=(DataList &&other)
+    DataList &operator=(DataList &&other) noexcept
     {
       key_length_ = other.key_length_;
       value_      = std::move(other.value_);

api/include/opentelemetry/context/runtime_context.h

@@ -58,6 +58,8 @@ public:
    */
   virtual bool Detach(Token &token) noexcept = 0;
 
+  virtual ~RuntimeContextStorage(){};
+
 protected:
   nostd::unique_ptr<Token> CreateToken(const Context &context) noexcept
   {